I have a text file that contains a path. The path can be anything and can contain many different exotic characters. For the sake of example let's say it contains this:
C:\России общий приговор\file.dat
Now I'm using wifstream to fetch the line...
wifstream myfile(path_to_txt_file);
wstring path = L"";
if (!getline(myfile, path)) cout << "Couldn't open file!" << endl;
The problem arises when I want to check if the file in the path variable exists (I'm using Boost, but it doesn't really matter), it returns 0 even though it is present.
cout << boost::filesystem::exists(path) << endl; // 0
cout << boost::filesystem::exists(L"C:\\России общий приговор\\file.dat") << endl; // 1
Passing the variable in there returns 0, but hard-coding the path works, what's going on?
Do I need to set some locale settings? If so, how do I get this to work for everyone? Russian, Chinese, Swedish etc.
Related
I am relatively new to programming and this project is one of the very first projects that I am doing in my own time.
I am basically trying to make a login registration program that hashes user-entered data and stores it in a text file. The login option basically accesses that text file and compares it with the user entered data to see if there exists any such username and password combinations. The registration option basically writes the user data into the file. I am not very far into the project since I want to add a few more "features" to the program so it works a bit better. Currently, however, I encountered a slight problem while reading the data from the text file for the login option. Basically, one of the hashed passwords stored in the text file contains \x1a as a part of its hash. I think the program always ends whenever it reads this sub-control character since it reaches the end of the file. What I want to know is how to avoid a hash that has such a character.
I am using the crypto++ library (I am not too familiar with it).
The hash function:
void hashingFunc(string originalPass, string& hashedPass) {
using namespace CryptoPP;
SHA3_256 hash;
hash.Update((const byte*)originalPass.data(), originalPass.size());
encryptedPass.resize(hash.DigestSize());
hash.Final((byte*)&encryptedPass[0]);
}
The read function:
void readFileFunc(fstream& outputFile, const string FILE_NAME, string userNameHash, string passWordHash) {
string localUserHash;
string localPassHash;
if (!outputFile) {
cout << "File containing login information failed to open. Please try again." << endl;
cout << "If the problem persists, check file name and location." << endl;
cout << "File Name in the system: " << FILE_NAME << endl;
}
else {
while (outputFile) {
if (outputFile.eof())
break;
getline(outputFile, localUserHash);
getline(outputFile, localPassHash);
if (localUserHash == userNameHash) {
if (localPassHash == passWordHash) {
cout << "Successful Login!" << endl;
}
}
}
}
}
When I read in information via fstream, it has ocurred twice in two different programs, that the input given to my program isn't stable, even if a given file doesn't change.
In my most recent program, which is concerned with audio-reading. I'm doing a simple check on the first four letters in the file. These letters are supposed to be RIFF, which they also are - I checked.
So, in order to check the format of a given binary file, I buffer the first four letters and see if they are equal to 'RIFF'.
char buffer[4];
std::ifstream in(fn,std::ios::binary);
in.read(buffer,4);
if(buffer!="RIFF"){//Always wrong atm
std::cout << "INVALID WAV FILE: " << buffer << std::endl;
}
When I first made the program, I recall this working properly. Now though, I get an error via my own cout:
INVALID WAV FILE: RIFFýfK
Does anyone have any idea as to what has gone wrong? Perhaps a way to make fstream more consistent?
You're reading 4 characters but not adding a zero terminator, furthermore your comparison is wrong since you're not comparing strings equality, you should rather do:
char buffer[5];
std::ifstream in(fn, std::ios::binary);
in.read(buffer, 4);
buffer[4] = '\0'; // Add a zero-terminator at the end
if (strcmp(buffer,"RIFF")) { // If buffer isn't {'R','I','F','F','\0'}..
std::cout << "INVALID WAV FILE: " << buffer << std::endl;
}
As part of a bigger application I am working on a class for reading input from a text file for use in the initialization of the program. Now I am myself fairly new to programming, and I only started to learn C++ in December, so I would be very grateful for some hints and ideas on how to get started! I apologise in advance for a rather long wall of text.
The text file format is "keyword-driven" in the following way:
There are a rather small number of main/section keywords (currently 8) that need to be written in a given order. Some of them are optional, but if they are included they should adhere to the given ordering.
Example:
Suppose there are 3 potential keywords ordered like as follows:
"KEY1" (required)
"KEY2" (optional)
"KEY3" (required)
If the input file only includes the required ones, the ordering should be:
"KEY1"
"KEY3"
Otherwise it should be:
"KEY1"
"KEY2"
"KEY3"
If all the required keywords are present, and the total ordering is ok, the program should proceed by reading each section in the sequence given by the ordering.
Each section will include a (possibly large) amount of subkeywords, some of which are optional and some of which are not, but here the order does NOT matter.
Lines starting with characters '*' or '--' signify commented lines, and they should be ignored (as well as empty lines).
A line containing a keyword should (preferably) include nothing else than the keyword. At the very least, the keyword must be the first word appearing there.
I have already implemented parts of the framework, but I feel my approach so far has been rather ad-hoc. Currently I have manually created one method per section/main keyword , and the first task of the program is to scan the file for to locate these keywords and pass the necessary information on to the methods.
I first scan through the file using an std::ifstream object, removing empty and/or commented lines and storing the remaining lines in an object of type std::vector<std::string>.
Do you think this is an ok approach?
Moreover, I store the indices where each of the keywords start and stop (in two integer arrays) in this vector. This is the input to the above-mentioned methods, and it would look something like this:
bool readMAINKEY(int start, int stop);
Now I have already done this, and even though I do not find it very elegant, I guess I can keep it for the time being.
However, I feel that I need a better approach for handling the reading inside of each section, and my main issue is how should I store the keywords here? Should they be stored as arrays within a local namespace in the input class or maybe as static variables in the class? Or should they be defined locally inside relevant functions? Should I use enums? The questions are many!
Now I've started by defining the sub-keywords locally inside each readMAINKEY() method, but I found this to be less than optimal. Ideally I want to reuse as much code as possible inside each of these methods, calling upon a common readSECTION() method, and my current approach seems to lead to much code duplication and potential for error in programming. I guess the smartest thing to do would simply be to remove all the (currently 8) different readMAINKEY() methods, and use the same function for handling all kinds of keywords. There is also the possibility for having sub-sub-keywords etc. as well (i.e. a more general nested approach), so I think maybe this is the way to go, but I am unsure on how it would be best to implement it?
Once I've processed a keyword at the "bottom level", the program will expect a particular format of the following lines depending on the actual keyword. In principle each keyword will be handled differently, but here there is also potential for some code reuse by defining different "types" of keywords depending on what the program expects to do after triggering the reading of it. Common task include e.g. parsing an integer or a double array, but in principle it could be anything!
If a keyword for some reason cannot be correctly processed, the program should attempt as far as possible to use default values instead of terminating the program (if reasonable), but an error message should be written to a logfile. For optional keywords, default values will of course also be used.
In order to summarise, therefore, my main questions are the following:
1. Do you think think my approach of storing the relevant lines in a std::vector<std::string> to be reasonable?
This will of course require me to do a lot of "indexing work" to keep track of where in the vector the different keywords are located. Or should I work more "directly" with the original std::ifstream object? Or something else?
2. Given such a vector storing the lines of the text file, how I can I best go about detecting the keywords and start reading the information following them?
Here I will need to take account of possible ordering and whether a keyword is required or not. Also, I need to check if the lines following each "bottom level" keyword is in the format expected in each case.
One idea I've had is to store the keywords in different containers depending on whether they are optional or not (or maybe use object(s) of type std::map<std::string,bool>), and then remove them from the container(s) if correctly processed, but I am not sure exactly how I should go about it..
I guess there is really a thousand different ways one could answer these questions, but I would be grateful if someone more experienced could share some ideas on how to proceed. Is there e.g. a "standard" way of doing such things? Of course, a lot of details will also depend on the concrete application, but I think the general format indicated here can be used in a lot of different applications without a lot of tinkering if programmed in a good way!
UPDATE
Ok, so let my try to be more concrete. My current application is supposed to be a reservoir simulator, so as part of the input I need information about the grid/mesh, about rock and fluid properties, about wells/boundary conditions throughout the simulation and so on. At the moment I've been thinking about using (almost) the same set-up as the commercial Eclipse simulator when it comes to input, for details see
http://petrofaq.org/wiki/Eclipse_Input_Data.
However, I will probably change things a bit, so nothing is set in stone. Also, I am interested in making a more general "KeywordReader" class that with slight modifications can be adapted for use in other applications as well, at least it can be done in a reasonable amount of time.
As an example, I can post the current code that does the initial scan of the text file and locates the positions of the main keywords. As I said, I don't really like my solution very much, but it seems to work for what it needs to do.
At the top of the .cpp file I have the following namespace:
//Keywords used for reading input:
namespace KEYWORDS{
/*
* Main keywords and corresponding boolean values to signify whether or not they are required as input.
*/
enum MKEY{RUNSPEC = 0, GRID = 1, EDIT = 2, PROPS = 3, REGIONS = 4, SOLUTION = 5, SUMMARY =6, SCHEDULE = 7};
std::string mainKeywords[] = {std::string("RUNSPEC"), std::string("GRID"), std::string("EDIT"), std::string("PROPS"),
std::string("REGIONS"), std::string("SOLUTION"), std::string("SUMMARY"), std::string("SCHEDULE")};
bool required[] = {true,true,false,true,false,true,false,true};
const int n_key = 8;
}//end KEYWORDS namespace
Then further down I have the following function. I am not sure how understandable it is though..
bool InputReader::scanForMainKeywords(){
logfile << "Opening file.." << std::endl;
std::ifstream infile(filename);
//Test if file was opened. If not, write error message:
if(!infile.is_open()){
logfile << "ERROR: Could not open file! Unable to proceed!" << std::endl;
std::cout << "ERROR: Could not open file! Unable to proceed!" << std::endl;
return false;
}
else{
logfile << "Scanning for main keywords..." << std::endl;
int nkey = KEYWORDS::n_key;
//Initially no keywords have been found:
startIndex = std::vector<int>(nkey, -1);
stopIndex = std::vector<int>(nkey, -1);
//Variable used to control that the keywords are written in the correct order:
int foundIndex = -1;
//STATISTICS:
int lineCount = 0;//number of non-comment lines in text file
int commentCount = 0;//number of commented lines in text file
int emptyCount = 0;//number of empty lines in text file
//Create lines vector:
lines = std::vector<std::string>();
//Remove comments and empty lines from text file and store the result in the variable file_lines:
std::string str;
while(std::getline(infile,str)){
if(str.size()>=1 && str.at(0)=='*'){
commentCount++;
}
else if(str.size()>=2 && str.at(0)=='-' && str.at(1)=='-'){
commentCount++;
}
else if(str.size()==0){
emptyCount++;
}
else{
//Found a non-empty, non-comment line.
lines.push_back(str);//store in std::vector
//Start by checking if the first word of the line is one of the main keywords. If so, store the location of the keyword:
std::string fw = IO::getFirstWord(str);
for(int i=0;i<nkey;i++){
if(fw.compare(KEYWORDS::mainKeywords[i])==0){
if(i > foundIndex){
//Found a valid keyword!
foundIndex = i;
startIndex[i] = lineCount;//store where the keyword was found!
//logfile << "Keyword " << fw << " found at line " << lineCount << " in lines array!" << std::endl;
//std::cout << "Keyword " << fw << " found at line " << lineCount << " in lines array!" << std::endl;
break;//fw cannot equal several different keywords at the same time!
}
else{
//we have found a keyword, but in the wrong order... Terminate program:
std::cout << "ERROR: Keywords have been entered in the wrong order or been repeated! Cannot continue initialisation!" << std::endl;
logfile << "ERROR: Keywords have been entered in the wrong order or been repeated! Cannot continue initialisation!" << std::endl;
return false;
}
}
}//end for loop
lineCount++;
}//end else (found non-comment, non-empty line)
}//end while (reading ifstream)
logfile << "\n";
logfile << "FILE STATISTICS:" << std::endl;
logfile << "Number of commented lines: " << commentCount << std::endl;
logfile << "Number of non-commented lines: " << lineCount << std::endl;
logfile << "Number of empty lines: " << emptyCount << std::endl;
logfile << "\n";
/*
Print lines vector to screen:
for(int i=0;i<lines.size();i++){
std:: cout << "Line nr. " << i << " : " << lines[i] << std::endl;
}*/
/*
* So far, no keywords have been entered in the wrong order, but have all the necessary ones been found?
* Otherwise return false.
*/
for(int i=0;i<nkey;i++){
if(KEYWORDS::required[i] && startIndex[i] == -1){
logfile << "ERROR: Incorrect input of required keywords! At least " << KEYWORDS::mainKeywords[i] << " is missing!" << std::endl;;
logfile << "Cannot proceed with initialisation!" << std::endl;
std::cout << "ERROR: Incorrect input of required keywords! At least " << KEYWORDS::mainKeywords[i] << " is missing!" << std::endl;
std::cout << "Cannot proceed with initialisation!" << std::endl;
return false;
}
}
//If everything is in order, we also initialise the stopIndex array correctly:
int counter = 0;
//Find first existing keyword:
while(counter < nkey && startIndex[counter] == -1){
//Keyword doesn't exist. Leave stopindex at -1!
counter++;
}
//Store stop index of each keyword:
while(counter<nkey){
int offset = 1;
//Find next existing keyword:
while(counter+offset < nkey && startIndex[counter+offset] == -1){
offset++;
}
if(counter+offset < nkey){
stopIndex[counter] = startIndex[counter+offset]-1;
}
else{
//reached the end of array!
stopIndex[counter] = lines.size()-1;
}
counter += offset;
}//end while
/*
//Print out start/stop-index arrays to screen:
for(int i=0;i<nkey;i++){
std::cout << "Start index of " << KEYWORDS::mainKeywords[i] << " is : " << startIndex[i] << std::endl;
std::cout << "Stop index of " << KEYWORDS::mainKeywords[i] << " is : " << stopIndex[i] << std::endl;
}
*/
return true;
}//end else (file opened properly)
}//end scanForMainKeywords()
You say your purpose is to read initialization data from a text file.
Seems you need to parse (syntax analyze) this file and store the data under the right keys.
If the syntax is fixed and each construction starts with a keyword, you could write a recursive descent (LL1) parser creating a tree (each node is a stl vector of sub-branches) to store your data.
If the syntax is free, you might pick JSON or XML and use an existing parsing library.
Hi I have some C++ code that uses user defined input to generate file-names for some output files:
std::string outputName = fileName;
for(int i = 0; i < 4; i++)
{
outputName.pop_back();
}
std::string outputName1 = outputName;
std::string outputName2 = outputName;
outputName.append(".fasta");
outputName1.append("_Ploid1.fasta");
outputName2.append("_Ploid2.fasta");
Where fileName could be any word the user can define with .csv after it e.g. '~/Desktop/mytest.csv'
The code chomps .csv off and makes three filenames / paths for 3 output streams.
It then creates them and attempts to open them:
std::ofstream outputFile;
outputFile.open(outputName.c_str());
std::ofstream outputFile1;
outputFile1.open(outputName1.c_str());
std::ofstream outputFile2;
outputFile2.open(outputName2.c_str());
I made sure to pass the names to open as const char* with the c_str method, however if I test my code by adding the following line:
std::cout << outputFile.is_open() << " " << outputFile1.is_open() << " " << outputFile2.is_open() << std::endl;
and compiling and setting fineName as "test.csv". I successfully compile and run, however,
Three zeros's are printed to screen showing the three filestreams for output are not in fact open. Why are they not opening? I know passing strings as filenames does not work which is why I thought conversion with c_str() would be sufficient.
Thanks,
Ben W.
Your issue is likely to be due to the path beginning with ~, which isn't expanded to /{home,Users}/${LOGNAME}.
ifstream open file C++
This answer to How to create a folder in the home directory? may be of use to you.
Unfortunately, there is no standard, portable way of finding out exactly why open() failed:
Detecting reason for failure to open an ofstream when fail() is true
I know passing strings as filenames does not work which is why I thought conversion with c_str() would be sufficient.
std::basic_ofstream::open() does accept a const std::string & (since C++11)!
I'm trying to find out if two strings I have are the same, for the purpose of unit testing. The first is a predefined string, hard-coded into the program. The second is a read in from a text file with an ifstream using std::getline(), and then taken as a substring. Both values are stored as C++ strings.
When I output both of the strings to the console using cout for testing, they both appear to be identical:
ThisIsATestStringOutputtedToAFile
ThisIsATestStringOutputtedToAFile
However, the string.compare returns stating they are not equal. When outputting to a text file, the two strings appear as follows:
ThisIsATestStringOutputtedToAFile
T^#h^#i^#s^#I^#s^#A^#T^#e^#s^#t^#S^#t^#r^#i^#n^#g^#O^#u^#t^#p^#u^#t^#
t^#e^#d^#T^#o^#A^#F^#i^#l^#e
I'm guessing this is some kind of encoding problem, and if I was in my native language (good old C#), I wouldn't have too many problems. As it is I'm with C/C++ and Vi, and frankly don't really know where to go from here! I've tried looking at maybe converting to/from ansi/unicode, and also removing the odd characters, but I'm not even sure if they really exist or not..
Thanks in advance for any suggestions.
EDIT
Apologies, this is my first time posting here. The code below is how I'm going through the process:
ifstream myInput;
ofstream myOutput;
myInput.open(fileLocation.c_str());
myOutput.open("test.txt");
TEST_ASSERT(myInput.is_open() == 1);
string compare1 = "ThisIsATestStringOutputtedToAFile";
string fileBuffer;
std::getline(myInput, fileBuffer);
string compare2 = fileBuffer.substr(400,100);
cout << compare1 + "\n";
cout << compare2 + "\n";
myOutput << compare1 + "\n";
myOutput << compare2 + "\n";
cin.get();
myInput.close();
myOutput.close();
TEST_ASSERT(compare1.compare(compare2) == 0);
How did you create the content of myInput? I would guess that this file is created in two-byte encoding. You can use hex-dump to verify this theory, or use a different editor to create this file.
The simpliest way would be to launch cmd.exe and type
echo "ThisIsATestStringOutputtedToAFile" > test.txt
UPDATE:
If you cannot change the encoding of the myInput file, you can try to use wide-chars in your program. I.e. use wstring instead of string, wifstream instead of ifstream, wofstream, wcout, etc.
The following works for me and writes the text pasted below into the file. Note the '\0' character embedded into the string.
#include <iostream>
#include <fstream>
#include <sstream>
int main()
{
std::istringstream myInput("0123456789ThisIsATestStringOutputtedToAFile\x0 12ou 9 21 3r8f8 reohb jfbhv jshdbv coerbgf vibdfjchbv jdfhbv jdfhbvg jhbdfejh vbfjdsb vjdfvb jfvfdhjs jfhbsd jkefhsv gjhvbdfsjh jdsfhb vjhdfbs vjhdsfg kbhjsadlj bckslASB VBAK VKLFB VLHBFDSL VHBDFSLHVGFDJSHBVG LFS1BDV LH1BJDFLV HBDSH VBLDFSHB VGLDFKHB KAPBLKFBSV LFHBV YBlkjb dflkvb sfvbsljbv sldb fvlfs1hbd vljkh1ykcvb skdfbv nkldsbf vsgdb lkjhbsgd lkdcfb vlkbsdc xlkvbxkclbklxcbv");
std::ofstream myOutput("test.txt");
//std::ostringstream myOutput;
std::string str1 = "ThisIsATestStringOutputtedToAFile";
std::string fileBuffer;
std::getline(myInput, fileBuffer);
std::string str2 = fileBuffer.substr(10,100);
std::cout << str1 + "\n";
std::cout << str2 + "\n";
myOutput << str1 + "\n";
myOutput << str2 + "\n";
std::cout << str1.compare(str2) << '\n';
//std::cout << myOutput.str() << '\n';
return 0;
}
Output:
ThisIsATestStringOutputtedToAFile
ThisIsATestStringOutputtedToAFile
It turns out that the problem was that the file encoding of myInput was UTF-16, whereas the comparison string was UTF-8. The way to convert them with the OS limitations I had for this project (Linux, C/C++ code), was to use the iconv() functions. To keep the compatibility of the C++ strings I'd been using, I ended up saving the string to a new text file, then running iconv through the system() command.
system("iconv -f UTF-16 -t UTF-8 subStr.txt -o convertedSubStr.txt");
Reading the outputted string back in then gave me the string in the format I needed for the comparison to work properly.
NOTE
I'm aware that this is not the most efficient way to do this. I've I'd had the luxury of a Windows environment and the windows.h libraries, things would have been a lot easier. In this case though, the code was in some rarely used unit tests, and as such didn't need to be highly optimized, hence the creation, destruction and I/O operations of some text files wasn't an issue.